题目

英语翻译
A pool cue striking a stationary billiary ball (mass= 0.25kg) gives the ball a speed of 2m/s.If the force of the cue on the ball was 25N,over what distance did this force act?
如果用动能定理的话直接是k=1/2 mv^2= 0.5*0.25kg*2m/s^2 = 0.5J
根据合外力所做的功等于动能 W= K ,W= fd,∴ d=k/f= 0.5J/25N =0.02m
所以移动了2cm
那如果用牛顿第二定律应该怎么做啊

提问时间：2020-11-02

答案

加速度 a = 25/0.25 = 100 m/s^2
根据 v2^2 - v1^2 = 2aS,有
2^2 - 0 = 2*100*S
S = 0.02 m